Need Help with Making Boat Go Faster

quickpros

Recruit
Joined
Aug 19, 2004
Messages
1
I have a 17'4" 95 Caravelle. It has a Ford 302 V8 <br />200HP engine in it. The prop is a LaserII 21Pitch. <br /> <br />If my speedometer is correct I can only get the boat <br />going 50mph and talking to some other boaters they <br />seem like it should go faster. One guy I talked to has a <br />21' with 200hp engine and his goes 75mph.<br /> <br />If the RPM gauge is correct it hits 5000 at full throttle. <br /> <br />What can I do to get the boat going 70mph or so? Some <br />have said it might be the gears in the lower unit. I am pretty <br />sure the lower unit is stock. Is it the prop? Gears?<br /><br />Thanks,<br /><br />Steve McCarty
 

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: Need Help with Making Boat Go Faster

That's a deep V hull, right? Unless you're talking about an outboard, anybody who says their 21' boat goes 75 with 200hp is full of s**t. It won't happen. 50mph sounds about right, but it's unlikely your speedometer is accurate. My 16' Glastron goes 50mph with a 150hp outboard, and inboards are allways slower HP for HP. Sounds like you've already got a good prop, so about the only way you're going to go faster is doing something to the engine for more power. I'm sure there are plenty of performance parts available for a 302.
 

cobra 3.0

Lieutenant Commander
Joined
Jul 31, 2003
Messages
1,797
Re: Need Help with Making Boat Go Faster

Isn't 5000 rpm a bit high for a 302? I'd try a higher pitch prop for more speed.
 

cuzner

Senior Chief Petty Officer
Joined
Feb 14, 2004
Messages
771
Re: Need Help with Making Boat Go Faster

If your hitting 5000 rpm with a 21p prop you should be able to prop up to 23p.It won't give much more speed though, maybe 3-5 mph. 75 mph with a 200hp engine? maybe if he has it on a canoe.<br /><br /> Jim
 

gsbodine

Petty Officer 1st Class
Joined
May 4, 2004
Messages
346
Re: Need Help with Making Boat Go Faster

Bet a GPS unit wouldn't say that. As mentioned above, boat speedometers are notoriously innaccurate for any number of reasons. Borrow a GPS (or buy one, for that matter) and check your speed (and "the other guy"'s, if you can). At least then you'll know it's an accurate reading and comparison.
 

f_inscreenname

Commander
Joined
Aug 23, 2001
Messages
2,591
Re: Need Help with Making Boat Go Faster

1973 Larson 17’ deep V with a built 302 (aprox 260hp ) would make 48mph with a 888 mercruiser outdrive. Same boat with a built 351W (aprox 300hp) would make about 53mph. Just watch hopping up a boat 302 motor. They break real easy under high stress. That's why I ended up installing a 351W. It held up real well.
 

datawire

Petty Officer 2nd Class
Joined
May 10, 2004
Messages
103
Re: Need Help with Making Boat Go Faster

75 MPH while being towed on the trailer sounds possible - but not too bright - to me.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,088
Re: Need Help with Making Boat Go Faster

What can I do to get the boat going 70mph or so?
I Agree.......<br />Other than On the Trailer, Going Down the Road,<br />This boat will Never See 70MPHs................<br /><br />Once you get to 50,<br />Anymore MPH is VERY Expensive...........
 

JasonJ

Rear Admiral
Joined
Aug 20, 2001
Messages
4,163
Re: Need Help with Making Boat Go Faster

You are talking close to doubling your speed. In order to get to where you want in speed, you would need to at least triple, if not quadruple your horsepower. That is not feasible. I think the person you are talking to is feeding you a line, has an inacurate speedo, or has fallen victim to the sensation that a person has on the water that makes it seem like it is going faster than it is. A rigged bassboat with a 300 horse outboard can get up around 80, an early Hydrostream Vector with 300 hp can get over 100, these have essentially the same hull, a high performance hull that allows the boat to litteraly run on a pad that is about a square foot in area. This pad and the prop are the only things in the water, that is what it needed to get speed. If your boat is a regular v hull with inboard, you will never see 70. You could get more horsepower and torque with some mods, mayber get it up around 250 hp, run a prop with more pitch, and get in the high 50s. After that, your wallet will vomit gallons of cash for little gain. My recommendation, just have fun with it. High speed in boats is fun for a couple minutes, after that the white knuckle factor has set in, and it is easy to get in trouble at high speeds. Also, if your lake is anything like mine, it has a speed limit (mine is 50mph) and it is pointless to has all that potential.
 

garycinn

Chief Petty Officer
Joined
Oct 7, 2003
Messages
479
Re: Need Help with Making Boat Go Faster

Originally posted by quickpros:<br /> What can I do to get the boat going 70mph or so?
You are trying to go 140mph in the family truckster. You need a sports car.<br /><br />Sell the Caravelle and get this:<br /><br /> http://www.allisonboats.com/XS_2003.html <br /><br />Quote from above web site: "Eighty plus M.P.H. is common with today's 150 horsepower motors"<br /><br />Twenty smackers and this one is yours:<br /><br /> http://adcache.boattraderonline.com/6/3/6/74478036.htm <br /><br />My BIL has one similar only with a 2.5L Merc Racing O/B. Tops out at about 105mph on a good day.
 
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